The Localization-Delocalization Transition in Quantum Dots

TL;DR

This paper investigates how electrons in quantum dots transition from localized states at low densities to delocalized states at higher densities, revealing boundary localization and unexpected electron binding phenomena.

Contribution

It provides experimental evidence of the localization-delocalization transition in quantum dots and describes the spatial behavior of electrons near this transition.

Findings

Electrons are localized at the perimeter at low densities.

Electrons become delocalized over the entire dot at higher densities.

Localized electrons at the boundary can bind with central electrons.

Abstract

Single-electron capacitance spectroscopy precisely measures the energies required to add individual electrons to a quantum dot. The spatial extent of electronic wavefunctions is probed by investigating the dependence of these energies on changes in the dot confining potential. For low electron densities, electrons occupy distinct spatial sites localized within the dot. At higher densities, the electrons become delocalized, and all wavefunctions are spread over the full dot area. Near the delocalization transition, the last remaining localized states exist at the perimeter of the dot. Unexpectedly, these electrons appear to bind with electrons in the dot center.